Clear anodize can be performed by most plating house. Grab the yellow pages and look up metal plating. Shop around and look for a respectable firm, someone doing mil-spec work can be a good sign.
This is a conversion process that changes the top coat of metal to a hard oxide. Try to avoid the lure of dyed anodize, the pigments will fade over time. Since this process is at the base metal, it does not suffer from the need to prep the materal via sandblasting like for powder coating.